Scopolamine infusion reduced heart rate variability and altered EEG metrics, including microstate D mean duration (p=0.039), corresponding to increased drowsiness and reduced excitation-inhibition.
Does scopolamine infusion alter EEG metrics and heart rate variability in adults?
Scopolamine infusion induces central EEG changes and peripheral HRV reductions consistent with Alzheimer's-like cholinergic disruption.
p-value: p=0.039
OBJECTIVE: Scopolamine disrupts cholinergic mechanisms via nonspecific muscarinic antagonism. Centrally, excitatory neocortical innervations are antagonised causing spectral electroencephalography (EEG) changes and cognitive impairment. Peripherally, parasympathetic control of heart rate variability (HRV) is disrupted, although acute HRV effects of scopolamine are not well-defined. METHODS: Forty adults with depression received scopolamine hydrobromide (N = 24, 4-6 μg/kg) or glycopyrronium bromide (N = 16, 4-6 μg/kg) infusions. Twelve healthy adults received scopolamine (4-6 μg/kg) infusions. EEG and electrocardiography were recorded across 4 hours post-infusion. EEG spectral, aperiodic, Lempel Ziv complexity (LZC), and microstates analyses were performed. Electrocardiographic HRV metric: proportion of high frequency power (pHF) was calculated and modelled via pharmacokinetic-pharmacodynamic models to ascertain the HRV concentration-effect relationship. RESULTS: ), and microstate D mean duration (t = -3.0, p = 0.039). EEG metrics correlated with drowsiness and alcohol-like stimulant ratings. Peripherally, scopolamine reduced HRV, with two-compartment pharmacokinetic models describing a delayed pHF effect via an effect compartment. CONCLUSIONS: These effects corresponded to increased drowsiness, reduced excitation-inhibition ratio, and reduced HRV-implicating central and peripheral muscarinic mechanisms reminiscent of Alzheimer's-like cholinergic disruption. TRIAL REGISTRATION: anzctr.org.au identifier: ACTRN12619000569101 and ACTRN12622000228785.
Chen et al. (Wed,) conducted a other in Depression (n=52). Scopolamine hydrobromide vs. Glycopyrronium bromide was evaluated on EEG metrics and heart rate variability (proportion of high frequency power) (p=0.039). Scopolamine infusion reduced heart rate variability and altered EEG metrics, including microstate D mean duration (p=0.039), corresponding to increased drowsiness and reduced excitation-inhibition.